Rod reducer instruments and methods

ABSTRACT

Rod reducers for use in orthopedic surgery are disclosed that include a fastener engaging member and a reducing member coupled together by an actuator assembly. The fastener engaging member can be secured to a fastener engaged to bone or tissue of the patient. The actuator assembly moves the reducing member such that its distal end contacts a rod and moves it toward the fastener.

FIELD OF THE INVENTION

The present invention concerns surgical instrumentation for moving onepart of a surgical implant into adjacent position or contact withanother. In particular, the invention contemplates rod reducerinstruments for use in placing or moving an orthopedic rod toward a bonefixation element.

BACKGROUND OF THE INVENTION

In the field of orthopedic surgery, and particularly spinal surgery, itis well known to correct an injury, malformation, or other defect by useof an implanted rod affixed to the body part to be corrected. Forexample, rod systems have been developed for correcting the positioningof and stabilizing the spine, and for facilitating fusion at variouslevels of the spine. In one such system, the rod is disposedlongitudinally along a length of the spine. The rod is preferably bent,either prior to or during surgery, to correspond to the normal curvatureof the spine in the particular region being instrumented, or to suchother curvature as the surgeon may deem appropriate to correct thedefect. For example, the rod can be bent to form a normal kyphoticcurvature for the thoracic region of the spine, or to form a normallordotic curvature for the lumbar region. The rod is engaged to a numberof fixation elements fixed to or engaged with the vertebrae along thesegment of the spinal column.

A variety of fixation elements can be provided that are configured toengage the vertebrae. For instance, one such fixation element is alaminar hook, configured to engage a lamina of the vertebra. Anotherprevalent fixation element is a spinal screw which can be threaded intoa pedicle or other portion of vertebral bone. Examples of such spinalscrews are seen in U.S. Pat. No. 5,005,562 to Cotrel, the disclosure ofwhich is incorporated herein by reference. An alternative type offixation element is a multi-axial bone screw, such as that as disclosedin U.S. Pat. Nos. 5,797,911 and 5,879,350 to Sherman et al., each ofwhich is also incorporated herein by reference in its entirety. Furthertypes of bone screws, hooks, bolts, or other fixation elements are knownin the art.

In one typical spinal procedure, an elongated implant (e.g. a rod) iscoupled to two or more fixation elements (e.g. bone screws) that arefixed to opposite sides of the spine or spinous processes. The bonescrews are first threaded into a portion of several vertebral bodies,such as the pedicles of these vertebrae. The rod is coupled to the bonescrews to provide corrective and stabilizing forces to the spine.Affixing a rod to a bone screw generally requires the rod to be in closeadjacent position or in contact with the screw. For example, withrespect to bone screws as disclosed in the Cotrel '562 patent and theSherman '911 and '350 patents identified above, a rod and an implantedscrew must be moved with respect to each other so that the rod occupiesspace within a channel or other opening in the screw. The rod is thencoupled to the implanted bone screw using a set screw, plug or otherappropriate fastener. The process of placing a rod within or adjacent toan implanted fixation element so that they can be coupled together istermed “reducing” the rod.

Rod reduction is commonly performed by a surgeon using his or her handsand/or rigid tools as pliers, levers or other instrumentation adaptableto create the necessary pushing and/or pulling forces on the implantedscrew and rod. Such procedures generally require the surgeon to placethe rod directly over the implanted fixation element, intersecting alongitudinal axis of the fixation element. Consequently, access to therod and the implanted fixation element along that axis, i.e. directlyabove the opening in the fixation element into which the rod is to beplaced, is necessary or at least highly desirable. However, such accesscan be difficult depending on such factors as the malformation to becorrected and the overall physiology of the patient, and can be verydifficult in procedures in which surgical invasiveness is to beminimized, as a result of the small ports or incisions of suchprocedures. Additionally, with use of mono-axial screws, the physiologyof the patient can require that the screw be placed at an angle suchthat the surgeon would have difficulty accessing and exerting force inthe necessary orientation on the rod and/or fixation element. Withmulti-axial fixation devices, the orientation of an unsecuredrod-receiving part of the fixation element can be even more varied withrespect to the rod and/or the surgeon. Consequently, the surgeon isstill frequently faced with the task of reducing a rod from an awkwardangle.

Various attempts in the prior art have been made in providing rodreducing instruments, such as described in U.S. Pat. No. 6,036,692 toBurel et al.; U.S. Pat. No. 5,910,141 to Morrison et al.; and U.S. Pat.No. 5,720,751 to Jackson; each of which is incorporated herein byreference in its entirety. However, needs remain in the industry for rodreducing instruments that can be used efficiently, safely and securelyin rod reduction procedures and for rod reduction instruments that canbe used in both minimally invasive and open surgical approaches to thesite of rod attachment.

SUMMARY OF THE INVENTION

The present invention provides instrumentation for rod reduction duringorthopedic surgery that are efficient and convenient to use. Theinstruments eliminate the need for direct application of manual force toa rod to position it in a desired location relative to a fastener. Theinstruments can also facilitate attachment of the rod to the fastener,and have application in both open surgical procedures and minimallyinvasive surgical procedures.

Aspects, objects, advantages, features, embodiments, and benefits of thepresent invention will be evident upon consideration of the followingwritten description and the accompanying figures, which illustrateembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of a rod reducer instrument inaccordance with one embodiment of the present invention shown in aretracted position.

FIG. 1a is an elevational view of an extension member useable with therod reducer instruments of the present invention.

FIG. 2 is a front elevational view of the rod reducer instrument of FIG.1 shown in a reducing position.

FIG. 3 is a side elevational view of the rod reducer instrument of FIG.2.

FIG. 4 is a front elevational view of a rod reducer instrument inaccordance with an alternate embodiment of the present invention shownin a retracted position.

FIG. 5 is a side elevational view of the rod reducer instrument of FIG.4 with a portion of its actuator assembly pivoted transversely.

FIG. 6 is a perspective view of a fastener engaging member comprising aportion of the rod reducer instrument of FIGS. 1 and 4.

FIG. 7 is a side elevational view of the fastener engaging member ofFIG. 6.

FIG. 8 is a side elevational view of the fastener engaging member ofFIG. 6 rotated ninety degrees about its longitudinal axis from its FIG.7 orientation.

FIG. 9 is a distal end elevational view of the fastener engaging memberof FIG. 6.

FIG. 10 is a perspective view of a reducing member comprising a portionof the rod reducer instrument of FIGS. 1 and 4.

FIG. 11 is a side elevational view of the reducing member of FIG. 10.

FIG. 12 is an elevational view of a link comprising a portion of the rodreducer instrument of FIGS. 1 and 4.

FIG. 13 is a perspective view of a first offset pivot arm comprising aportion of the rod reducer instrument of FIGS. 1 and 4.

FIG. 14 is an elevational view of the first offset pivot arm of FIG. 13.

FIG. 15 is an elevational view of the first offset pivot arm of FIG. 13rotated ninety degrees from its FIG. 13 orientation.

FIG. 16 is a perspective view of a second offset pivot arm comprising aportion of the rod reducer instrument of FIGS. 1 and 4.

FIG. 17 is an elevational view of the second offset pivot arm of FIG.16.

FIG. 18 is an elevational view of the second offset pivot arm of FIG. 16rotated ninety degrees from its FIG. 16 orientation.

FIG. 19 is a perspective view of a first arm comprising a portion of therod reducer instrument of FIG. 1.

FIG. 20 is a perspective view of a second arm comprising a portion ofthe rod reducer instrument of FIG. 1.

FIG. 21 is an elevational view of the proximal end of the second arm ofFIG. 20.

FIG. 22 is an enlarged elevation view of the proximal end of the secondarm rotated ninety degrees from its orientation in FIG. 21.

FIG. 23 is a perspective view of a releaser comprising a portion of therod reducer instrument of FIGS. 1 and 4.

FIG. 24 is a side elevational view of a ratchet arm comprising a portionof the rod reducer instrument of FIGS. 1 and 4.

FIG. 25 is a front elevational view of a rod reducer instrument inaccordance with a further embodiment of the present invention shown in aretracted position.

FIG. 26 is a side elevational view of the rod reducer instrument of FIG.25 shown in a reducing position and extending through an access port.

FIG. 27 is the rod reducer instrument of FIG. 25 shown in a reducingposition.

FIG. 28 is an elevational view of a fastener engaging member comprisinga portion of the rod reducer instrument of FIG. 25.

FIG. 29 is a cross-sectional view through line 29—29 of FIG. 28.

FIG. 30 is an enlarged view of the distal end of the fastener engagingmember of FIG. 28.

FIG. 31 is a cross-sectional view through line 31—31 of FIG. 28.

FIG. 32 is an elevational view of a reducing member comprising a portionof the rod reducer instrument of FIG. 25.

FIG. 33 is an elevational view of the reducing member of FIG. 32 rotatedninety degrees about its longitudinal axis from its orientation in FIG.32.

FIG. 34 is an elevational view looking at the proximal end of thereducing member of FIG. 32.

FIG. 35 is a plan view of a driving member comprising a portion of therod reducer instrument of FIG. 25.

FIG. 36 is a cross-sectional view taken through line 36—36 of FIG. 35.

FIG. 37 is a side elevational view of the driving member of FIG. 35.

FIG. 38 is an elevational view of a handle comprising a portion of therod reducer instrument of FIG. 25.

FIG. 39 is an elevational view of the handle of FIG. 38 rotated ninetydegrees about its longitudinal axis from its orientation in FIG. 38.

FIG. 40 is a cross-sectional view through line 40—40 of FIG. 39.

FIG. 41 is a cross-sectional view through line 41—41 of FIG. 38.

FIG. 42 is an elevational view of a stop member comprising a portion ofthe rod reducer instrument of FIG. 25.

FIG. 43 is an end elevational view of the stop member of FIG. 42.

FIG. 44 is an elevational view of a link comprising a portion of the rodreducer instrument of FIG. 25.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any such alterations and furthermodifications in the illustrated device, and any such furtherapplications of the principles of the invention as illustrated therein,are contemplated as would normally occur to one skilled in the art towhich the invention relates.

Referring to FIGS. 1-3, there is shown a first embodiment of a rodreducer instrument 50 according to the present invention. In normal usein the patient's body rod reducer instrument 50 is oriented so that itsactuator assembly 51 is located proximally, indicated by the letter “P”and accessible by the surgeon, and the opposite end of instrument 50 isoriented distally, indicated by the letter “D”, away from the surgeonand towards the operative site. In FIGS. 1-3, the operative site is avertebral body V1 of the spinal column in which a fastener F is engaged.Fastener F has a yoke Y that allows a rod R to be positioned therein andthen secured to fastener F with a set screw or the like. In order tofacilitate the surgeon's positioning of rod R in fastener F, rod reducerinstrument 50 is engageable to fastener F and positionable against rod Rand thereafter operable to move rod R in closer proximity to fastener Fsuch that rod R can be secured to fastener F. Fastener F can be amulti-axial or uni-axial screw, a hook, or other bone or tissue engagingdevice. Rod R can be any elongated implant element of any size or shapeso long as it can be secured to fastener F.

Rod reducer instrument 50 includes a fastener engaging member 80 and areducing member 100 coupled together by an actuator assembly 51 suchthat reducing member 100 is movable proximally and distally with respectto fastener engaging member 80. Fastener engaging member 80 isengageable to fastener F and reducing member 100 is movable to contactrod R and push it toward fastener F. In the illustrated embodiment,reducing member 100 is slidably disposed about fastener engaging member80, and rod R is captured in fastening engaging member 80 when reducingmember 100 is in a retracted position as shown in FIG. 1. Reducingmember 100 is movable distally with respect to fastener engaging member80 by actuator assembly 51 to contact rod R and position rod R into yokeY of fastener F as shown in FIGS. 2 and 3. Fastener engaging member 80has a passage 82 (FIG. 7) extending therethrough through which a setscrew or cap and a driver (not shown) can be extended to engage the setscrew to yoke Y and securing rod R therein.

With further reference to FIGS. 6-9 in conjunction with FIGS. 1-3,fastener engaging member 80 will now be further described. In theillustrated embodiment, fastener engaging member 80 includes a body 84having a longitudinal axis 86 and an enlarged distal portion 88.Although body 84 is shown as having a generally cylindricalcross-section perpendicular to axis 86, it is understood that body 84can have a cross-section of any appropriate shape, such as oval, square,or regularly or irregularly polygonal. Body 84 is hollow in a preferredembodiment, having passage 82 extending between and opening at proximalend 87 and distal end 89 of body 84.

Body 84 also includes first and second flex arms 90 and 92. In theillustrated embodiment, flex arms 90 and 92 have slots 91 and 93extending therebetween. Slot 91 includes a relieved portion 91 a andslot 93 includes a relieved portion 93 a to facilitate flexion of flexarms 90 and 92 away from one another as distal portion 88 is positionedover yoke Y of fastener F. In the illustrated embodiment, distal portion88 includes prongs 94 and 96 through which slots 91 and 93 extend. Eachprong 94, 96 includes a rod channel 94 a, 96 a in communication withslots 91, 93 and configured to receive rod R therein. Flex arms 90 and92 can be apart in their natural state, so that they can be squeezedtogether by reducing member 100 contacting the enlarged distal portion88 to hold a fastener F therein, and released to move apart from eachother and release fastener F. Alternatively, flex arms 90, 92 can betogether in their natural state, so that they can be forced apart byinsertion of a fixation element or other application of force, and willnaturally clamp on or around fastener F.

Prongs 94 and 96 are substantially identically configured, and thereforethey will both be described by reference to prong 96 as shown in FIGS. 7and 9. Prong 96 includes a wall 96 b that surrounds a portion of rodchannel 96 a. Prong 94 also has interior surfaces 96 c and 96 dextending between respective ones of the slots 91 and 93 and rod channel96 a. Interior surfaces 96 c and 96 d are sized and shaped to match theprofile of the portion of yoke Y of fastener F that is positionablethereagainst. Extending from interior surfaces 96 c and 96 d areprotrusions 96 e and 96 f, respectively. Protrusions 96 d and 96 f havea size, shape and depth that allows insertion into an indentation orhole formed in yoke Y of fastener F. For example, the multi-axial bonescrew disclosed in U.S. Pat. No. 5,797,911 includes four opposed roundindentations in its exterior portion. Protrusions 96 e and 96 f, alongwith the identical protrusions on prong 94, are designed to fit intothese indentations. However, it should be understood that prongs 94 and96 can be configured to fit other sizes, shapes or depths ofindentations, or otherwise to connect to other bone fixation elements.

It will be understood that fastener engaging member 80 need not includeflex arms 90, 92, but rather be a formed from a substantially solid bodyhaving an appropriately-shaped socket distal end for engaging fastener Fand including a rod channel which receives rod R. Such a solid bodycould also include spring-loaded protrusions that allow passage of thedistal end over yoke Y until the protrusions engage in the correspondingindentations. Furthermore, such a distal end could include only a pairof protrusions on the inner wall oriented toward rod channels 94 a, 94 band engage indentations or holes formed on corresponding locations ofyoke Y of fastener F, such as shown in the aforementioned '911 patent.Other means for connecting fastener engaging member 80 to fastener F arealso contemplated, including a snap rings, set screws, or aninterference fit, to name a few.

Proximal end 87 of fastener engaging member 80 further includes alateral extension 98 having a hole 98 a formed therein. As shown in FIG.3, this hole 98 a of lateral extension 98 receives a pin or fastener 99to couple fastener engaging member 80 to actuator assembly 51. Fastenerengaging member 80 is coupled to actuator assembly 51 such that fastenerengaging member 80 remains stationary while components of actuatorassembly 51 pivot about fastener 99.

Rod reducer instrument 50 further includes reducing member 100positioned about fastener engaging member 80. Referring now to FIGS.10-11 in conjunction with FIGS. 1-3, reducing member 100 includes asubstantially cylindrical body 104 extending between a proximal end 106and a distal end 108. Reducing member 100 also includes an internalpassage 102 extending along longitudinal axis 116 between and opening atproximal end 106 and distal end 108. Passage 102 of reducing member 100is dimensioned to be slidable with respect to fastener engaging member80. Reducing member 100 further includes a first ear 110 and adiametrically opposite ear 112. Ears 110 and 112 are pivotally coupledto actuator assembly 51.

Passage 102 can include distal portion 102 a defined by an extensionportion 104 a of body 104. Passage 102 also includes a proximal portion102 b in communication with distal portion 102 a and opening at proximalend 106. Distal portion 102 a is larger in diameter than proximalportion 102 b and is sized to receive enlarged distal portion 88 offastener engaging member 80 therein. A lip 102 c is defined betweendistal portion 102 a and proximal portion 102 b and contacts enlargedrim 88 a to limit the distance of distal movement of reducing member 100with respect to fastener engaging member 80. The length L2 of passage102 a and extension 104 a of reducing member 100 can vary from 0millimeters up to 20 millimeters or more, thus allowing the surgeon toselect a rod reducer instrument 50 having an extension 104 a/distalpassage 102 a of appropriate length for the distance of rod reductionbeyond distal end 89 that is desired. It is further contemplated thatproximal portion 102 b can include a further inwardly stepped portion orother means for contacting or reducing the spacing between fastenerengaging member 80 and reducing member 100 to limit the amount of wobbleor play of reducing member 100 with respect to fastener engaging member80.

In procedures using multiple fasteners F along the spine, yokes Y canhave extended lengths from the head of fastener F that allows rod R tobe spaced at various distances from each fastener F. The ability toselect from rod reducer instruments having different extension lengthsL2 enables the spacing between each fastener F and rod R in yoke Y to becontrolled and varied, such as would be desirable in a spondylolisthesisreduction technique. After the desired rod position in the extended yokeY is obtained, a set screw is placed through passage 82 and into yoke Yto maintain rod R at this desired position.

In another form, rod reducer instrument 50 has a passage 102 with adistal portion 102 a that is sized to engage enlarged distal portion 88of fastener engaging member 80. Distal end 88 contacts enlarged rim 88 ato limit the amount of distal displacement of reducing member 100.Proximal portion 102 b fits closely around fastener engaging member 80to limit or eliminate wobble or play of reducing member 100 with respectto fastener engaging member 80. In order to adapt this form of rodreducer instrument 50 for spondylolisthesis procedures, an extensionmember 500 is provided as shown in FIG. 1a. Extension member 500 has abody 502 with a rim 504 about a proximal end thereof to facilitateplacement and removal over reducing member 100. Extension member 500 hasa passage 506 extending between and opening at the proximal end 510 andthe distal end 512 of extension member 500. Passage 506 is configured sothat extension member 500 can be positioned about reducing member 100with its proximal end adjacent ears 118, 119 and held with respectthereto via frictional engagement, threaded engagement, a set screw orthe like. Extension member 500 has a distal portion 516 about distalpassage portion 506 a that has length L3 which extends beyond distal end108 of reducing member 100 to allow reduction of rod R distally beyonddistal end 108. Length L3 can provided in any increment of 1 millimeteror more. It is further contemplated that rod reducer instrument 50 canbe provided in a kit with a number of extension members 500 havingdifferent lengths L3 to allow the surgeon to select the amount of rodreduction desired beyond distal end 108 of reducing member 100. In use,rod reducer instrument 50 is used without extension 500 for initialreduction of rod R into the elongated yoke Y and the rod isprovisionally secured in this initial position with a set screw. Anextension member 500 of desired length is then placed over reducingmember 100 and rod R is further reduced to a desired position and theset screw advanced into the yoke to secure rod R in its desiredposition.

Actuator assembly 51 includes a first arm 52 and a second arm 54, and isoperable to selectively move reducing member 100 proximally and distallyalong fastener engaging member 80 with longitudinal axes 86 and 116substantially aligned. Contact between the distal ends 58, 59 of arms52, 54 of actuator assembly 51 prevent reducing member 100 from beingretracted too far proximally. As reducing member 100 is moved distally,its distal end 108 contacts rod R and moves it distally towards fastenerF. The surgeon can then insert the set screw or cap through passage 82of fastener engaging member 80 to secure rod R in yoke Y. Passage 82 canbe sized and configured to closely fit with the driver used to installthe set screw to ensure proper alignment between the set screw and theyoke. Reducing member 100 can be provided with slots 114, 115 that arealignable with slots 91, 93 of fastener engaging member 80. This allowsthe surgeon to visualize passage 82 and the internal portion of yoke Yduring rod reduction and set screw placement to verify proper alignmentand positioning. Extension member 500 could also be provided with slots514 through its body 504 to allow such visualization when it is used.

First ear 110 can be provided with a female receptacle 111 into whichone end of a first link 120 of actuator assembly 51 can be placed.Sirilarly, second ear 112 can be provided with a female receptacle 113into which one end of a second link 122 of actuator assembly 51 can beplaced. First and second links are identical, and will be describedfurther with reference to first link 120 shown in FIG. 12. Link 120includes a body 124 having first hole 126 at one end thereof and asecond hole 128 at an opposite end thereof. First hole 126 is alignablewith first ear holes 110 a of first ear 110, and the first hole ofsecond link 122 is similarly alignable with second ear holes 112 a ofsecond ear 112. Links 122, 124 are pivotally secured to ears 110, 112,respectively, via pins 118, 119 respectively.

Second hole 128 of link 120 is pivotally connected to a first offsetpivot arm 130 of actuator assembly 51 by pin 127, and the identicalsecond hole of second link 122 is pivotally coupled to second offsetpivot arm 140 of actuator assembly 51 by pin 129. Referring now to FIGS.13-15 along with FIGS. 1-3, first offset pivot arm 130 includes a body131 defining a lateral offset L to position the proximal portion ofactuator assembly 51 away from passage 82 of fastener engaging member80. Body 131 has a distal end 132 defining a female receptacle 132 a andholes 132 b extending therethrough in communication with femalereceptacle 132 a. First link 120 is positionable in female receptacle132 a with its second hole aligned with holes 132 b. Body 131 extendsfrom distal end 132 to proximal end 134 and forms a lateral offset Ltherebetween, as discussed further below with respect to second offsetpivot arm 140. Proximal end 134 includes a proximal male connector 134 ahaving a hole 134 b formed therethrough. Proximal male connector 134 ais stepped down to a reduced thickness from body portion 131 tofacilitate pivotal engagement with a female receptacle 58 a at distalend 58 of first arm 52 of actuator assembly 51.

Referring now to FIGS. 16-18 along with FIGS. 1-3, second offset pivotarm 140 includes a body 141 defining a lateral offset L to position theproximal portion of actuator assembly 51 away from passage 82 offastener engaging member 80. Body 141 has a distal end 142 defining afemale receptacle 142 a and holes 142 b extending therethrough incommunication with female receptacle 142 a. Second link 122 ispositionable in female receptacle 142 a with its second hole alignedwith holes 142 b. Body 141 extends from distal end 142 to proximal end144 and forms a lateral offset L therebetween that is the same as theoffset L for first offset pivot arm 130. In one specific embodiment,lateral offset L is about 17 millimeters; however, it should beunderstood that other lateral offset distances are also contemplated,ranging from no lateral offset up to 30 millimeters or more. Proximalend 144 includes a proximal male connector 144 a having a hole 144 bformed therethrough. Proximal male connector 144 a is stepped down to areduced thickness from body portion 141 to facilitate pivotal engagementwith a female receptacle 59 a at distal end 59 of second arm 54 ofactuator assembly 51.

As shown in FIGS. 16-18, second offset pivot arm 140 includes a medialmale connector 146 adjacent proximal end 144 that is stepped down to areduced thickness from body 141. Medial male connector 146 includes ahole 146 a extending therethrough. Referring to FIGS. 13-15, firstoffset pivot arm 130 includes a medial female connector 136 adjacentproximal end 134 that defines a female receptacle 136 a sized to receivemedial male connector 146 of second offset pivot arm 140. Medial femaleconnector 136 includes holes 136 b extending therethrough incommunication with female receptacle 136 a. Fastener 99 is extendablethrough holes 136 b and hole 146 a to pivotally couple first offsetpivot arm 130 to second offset pivot arm 140. As discussed above,fastener 99 is also attached to hole 98 a of lateral extension 98 tosecure fastener engaging member 80 to actuator assembly 51 whileallowing first offset pivot arm 130 and second offset pivot arm 140 topivot with respect thereto.

Referring now to FIGS. 19 and 20, first arm 52 and second arm 54 ofactuator assembly 51 will be described. First arm 52 extends betweenproximal end 56 and distal end 58 and can include an arcuate profiletherealong to accommodate the hands and fingers of a surgeon's grip.Distal end 58 includes female receptacle 58 a having holes 58 b incommunication therewith. Female receptacle 58 a is sized to receiveproximal male connector 134 a of first offset pivot arm 130 therein. Pin139 extends through holes 58 b and hole 134 b of first offset pivot arm130 to pivotally couple first arm 52 thereto. Second arm 54 extendsbetween proximal end 57 and distal end 59 and can include an arcuateprofile therealong to accommodate the hands and fingers of a surgeon'sgrip. Distal end 59 includes female receptacle 59 a having holes 59 b incommunication therewith. Female receptacle 59 a is sized to receiveproximal male connector 144 a of second offset pivot arm 140 therein.Pin 149 extends through holes 59 b and hole 144 b of second offset pivotarm 140 to pivotally couple second arm 54 thereto.

First arm 52 has a medially extending male connector 62 defining a hole62 a therethrough. Second arm 54 has a medially extending femaleconnector 64 defining a receptacle (not shown) in communication withholes 64 a. The receptacle of female connector 64 is sized to receivemale connector 62, and a pin 65 extends through holes 64 a and 62 a topivotally couple first arm 52 and second arm 54 to one another.

Rod reducer instrument 50 includes a locking mechanism that holdsactuator assembly 51 in a closed position such as shown in FIG. 2. Whilea specific locking mechanism will be described, it should be understoodthat the present invention contemplates other means of holding actuatorassembly 51 in a closed position.

Proximal end 57 of second arm 54 further includes a tip 66 that isstepped down to a reduced thickness from that of second arm 54. Tip 66includes a hole 66 a formed therein and a finger 66 b extendingproximally therefrom and pointing laterally away from-first arm 52.Proximal end 56 of first arm 52 has a hole 60 formed in a medial sidethereof into which ratchet bracket 68 (FIG. 1) can be secured via apress fit, threaded connection, welded connection or the like. Ratchet70 is pivotally coupled to ratchet bracket 68 and extends medially fromfirst arm 52 toward second arm 54. As shown in further detail in FIG.24, ratchet 70 includes a hole 70 a through which a pin can be placed topivotally couple ratchet 70 to ratchet bracket 68. Ratchet 70 furtherincludes a number of teeth 70 b, 70 c, 70 d, 70 e each of which caninterlock with finger 66 b to hold actuator assembly 51 in a closedposition.

Rod reducer instrument 50 further includes a leaf spring 72 extendingbetween and engaged to the medial sides of first arm 52 and second arm54 to provide a biasing force that normally biases actuator assembly 51to an open position. Leaf spring 72 includes a first end 72 a extendingthrough ratchet bracket 68 and away from first arm 52 to contact aninclined end wall 70 f of ratchet 70 to normally bias medial end 70 g ofratchet 70 in the distal direction. When actuator assembly 51 is closed,first arm 52 is adjacent second arm 54 as shown in FIG. 2, and one ofthe teeth of ratchet 70 engages finger 66 b of second arm 54. First end72 a of spring 72 biases ratchet 70 toward finger 66 b to maintain thisengagement.

To facilitate disengagement of ratchet 70 and finger 66 b, a thumbrelease lever 74 is provided that is pivotally coupled to tip 66. Lever74 has a hole 74 a through which a pin may be placed to pivotally couplelever 74 to hole 66 a of tip 66. Lever 74 includes a press member 74 band an opposite nub 74 c. When arms 52, 54 are in their closed positionas shown in FIG. 2, press member 74 can be pushed distally, therebyraising nub 74 c into contact with ratchet 70 and lifting ratchet 70 offof finger 66 b to allow arms 52, 54 to return to their normally biasedopen position of FIG. 1. Wall 66 c of tip 66 blocks distal pivotingmovement of nub 74 c.

A method for using rod reducer instrument 50 will now be described. Thesurgeon has positioned fastener F into vertebra V1 and placed rod R inthe proximity of yoke Y of fastener F. Rod reducer instrument 50 is inits normally biased open position of FIG. 1 in which arms 52, 54 formangle A. In one specific embodiment, angle A is 45 degrees; howeverother values for angle A are also contemplated. Rod reducer instrument50 is introduced through an open incision or an access port to fastenerF. Fastener engaging member 80 is placed around rod R so that rod R isin rod channels 94 a, 96 a. Distal portion 88 is placed over yoke Y, andflex arms 90, 92 allow prongs 94, 96 to move outwardly to pass over yokeY until protrusions 94 e, 94 f, 96 e, 96 f engage indentations in yokeY. It is further contemplated that flex arms 90, 92 can be bent awayfrom one another and predisposed to an open position such that distalportion 88 is loosely positioned over yoke Y and reducing member 100moves distally along flex arms 90, 92 and distal portion 88 and pushesflex arms 90, 92 together to allow protrusions 94 e, 94 f, 96 e, 96 f toengage indentations in yoke Y.

With rod R in rod channels 94 a, 96 a and distal portion 88 secured toyoke Y, arms 52, 54 are moved towards one another against the bias ofspring 72 until ratchet 70 engages finger 66 b. As arms 52, 54 ofactuator assembly 51 are moved toward one another, reducing member 100moves distally along fastener engaging member 80 to push or reduce rod Rinto yoke Y a sufficient distance to allow attachment of a set screw orcap to yoke Y.

The distal movement of reducing member 100 is effected by distal ends58, 59 of arms 52, 54, respectively, moving away from one another, whichthereby pivots lateral offset pivot arms 130, 140 about fastener 99 sothat proximal ends 134, 144 move away from one another and distal ends132, 142 move towards one and distally, thereby pushing first and secondlinks 120, 122 distally and effecting distal movement of reducing member100 through the pivotal connection between ears 110, 112 and links 120,122. Reducing member 100 also engages the enlarged distal portion 88 offastener engaging member 80 thereby increasing the grip of prongs 94, 96on yoke Y. The locked actuator assembly 51 holds rod R in its reducedposition as the surgeon installs the set screw in yoke Y through passage82 of fastener engaging member 80. The lateral offset provided by pivotarms 130, 140 facilitate surgeon access since arms 52, 54 are positionedaway from the proximal end opening of fastener engaging member 80. Oncethe set screw is firmly seated in yoke Y, and preferably seated againstrod R, lever 74 is pressed to release ratchet 70 from finger 66 b soarms 52, 54 and reducing member 100 return to their open position ofFIG. 1. Flex arms 90 and 92 allow prongs 94, 96 to be flexed open andrelease protrusions 94 e, 94 f, 96 e, 96 f from yoke Y. Rod reducerinstrument 50 can then be removed and the procedure repeated as neededto reduce rod R into other fasteners.

Referring now to FIGS. 4 and 5, an alternate embodiment rod reducerinstrument 150 is provided. Except as otherwise discussed herein, rodreducer instrument 150 is identical to rod reducer instrument 50, andelements of rod reducer instrument 150 that are the same as the elementsof rod reducer instrument 50 are similarly designated but have “100”added to the reference numeral used for that element in the descriptionof rod reducer 50. Rod reducer instrument 150 includes a first arm 152having a proximal portion 152 a pivotally coupled to a distal portion152 b. Rod reducer instrument 150 further has a second arm 154 having aproximal portion 154 a pivotally coupled to a distal portion 154 b. Asshown in FIG. 5, this pivotal connection allows proximal portions 152 a,154 a to be pivoted in the same direction transversely to distalportions 152 b, 154 b and away from passage 182 of fastener engagingmember 180, providing the surgeon additional room to access passage 182.Further, the pivoted arm portions 152 a, 154 a can be used as thesurgeon as a means to provide a counter-torque as the set screw istightened onto rod R.

Rod reducer instrument 150 further includes an adjustment mechanism 250that allows fine control over movement of first arm 152 and second arm154 relative to one another. Adjustment mechanism 250 include a thumbnut 252 coupled to a threaded shaft 254. Threaded shaft 254 is pivotallycoupled to the medial side of first arm 152 and extends through a holeprovided through second arm 154. Thumb nut 252 is positioned on thelateral side of second arm 154. In order to move first arm 152 andsecond arm 154 towards one another, thumb nut 252 can be threadinglyadvanced along threaded shaft 254 towards first arm 152. In order tomove first arm 152 and second arm 154 away from one another, thumb nut252 can be threadingly retracted along threaded shaft 254 away fromfirst arm 152.

Referring to FIGS. 25-27, there is shown a further embodiment of a rodreducer instrument 350 according to the present invention. In normal usein the patient's body rod reducer instrument 350 is oriented so that itsactuator assembly 351 is oriented proximally, indicated by the letter“P” and accessible by the surgeon, and the opposite end of instrument350 is oriented distally, indicated by the letter “D”, away from thesurgeon and towards the operative site.

Rod reducer instrument 350 includes a fastener engaging member 380 and areducing member 400 coupled together by an actuator assembly 351 suchthat reducing member 400 is movable proximally and distally with respectto fastener engaging member 380. Fastener engaging member 380 isengageable to fastener F and reducing member 400 is movable to contactrod R and push it toward fastener F. In the illustrated embodiment,reducing member 400 is slidably disposed about fastener engaging member380, and rod R is captured in fastening engaging member 380 whenreducing member 400 is in a retracted position as shown in FIG. 25.Reducing member 400 is movable distally with respect to fastenerengaging member 380 by actuator assembly 351 to contact rod R andposition rod R into yoke Y of fastener F as shown in FIGS. 26 and 27.Fastener engaging member 380 has a passage 382 (FIG. 29) extendingtherethrough through which a set screw or cap and a driver (not shown)can be extended to engage the set screw to yoke Y and securing rod Rtherein.

With further reference to FIGS. 28-31 in conjunction with FIGS. 25-27,fastener engaging member 380 will now be further described. In theillustrated embodiment, fastener engaging member 380 includes a body 384having a longitudinal axis 386 and a distal portion 388. Although body384 is shown as having a generally cylindrical cross-sectionperpendicular to axis 386, it is understood that body 384 can have across-section of any appropriate shape, such as oval, square, orregularly or irregularly polygonal. Body 384 is hollow in a preferredembodiment, having passage 382 extending between and opening at proximalend 387 and distal end 389 of body 384.

Body 384 also includes first and second flex arms 390 and 392. In theillustrated embodiment, flex arms 390 and 392 have slots 391 and 393extending therebetween. Slots 391 and 393 facilitate flexion of flexarms 390 and 392 away from one another as distal portion 388 ispositioned over yoke Y of fastener F. In one embodiment, the distal endopening is tapered at angle B (FIG. 30) to facilitate passage over yokeY of fastener F. In one specific embodiment, angle B is ninety degrees,however other taper angles are also contemplated. Each slot 391, 393forms a channel sized to receive rod R therein. Flex arms 390 and 392can be apart in their natural state, so that they can be squeezedtogether by reducing member 400 to hold fastener F therein, and releasedto move apart from each other and release fastener F. Alternatively,flex arms 390, 392 can be together in their natural state, so that theycan be forced apart by insertion of a fixation element or otherapplication of force, and will naturally clamp on or around fastener F.

Flex arms 390 and 392 can each further include an inner profile sizedand shaped to match the profile of the portion of yoke Y of fastener Fthat is positionable therein. Extending inwardly from flex arms 390 and392 are protrusions 394 and 396, respectively. Protrusions 394 and 396have a size, shape and depth that allows insertion into an indentationor hole formed in yoke Y of fastener F. For example, the multi-axialbone screw disclosed in U.S. Pat. No. 5,797,911 includes twodiametrically opposed indentations in its exterior portion. However, itshould be understood that flex arms 390 and 392 can be configured to fitother sizes, shapes or depths of indentation, or otherwise to connect toother bone fixation elements.

It will be understood that fastener engaging member 380 need not includeflex arms 390, 392, but rather be formed from a substantially solid bodyhaving an appropriately-shaped socket distal end for engaging fastener Fand including a rod channel to receive rod R. Such a solid body couldalso include spring-loaded protrusions that allow passage of the distalend over yoke Y until the protrusions engage in the correspondingindentations. Furthermore, such a distal end could include fourprotrusions as described above with respect to rod reducer instrument50. Other means for connecting fastener engaging member 380 to fastenerF are also contemplated, including snap rings, set screws, or aninterference fit, to name a few.

Fastener engaging member 380 further includes a first ear 396 extendinglaterally therefrom having a hole 396 a formed therethrough and a secondear 398 extending laterally therefrom having a hole 398 a formedtherethrough. As shown in FIG. 25, these ears 396, 398 extend throughreducing member 400 for pivotal engagement to actuator assembly 351.

Referring now to FIGS. 32-34 in conjunction with FIGS. 25-27, reducingmember 400 includes a substantially cylindrical body 404 extendingbetween a proximal end 406 and a distal end 408. Reducing member 400also includes an internal passage 402 extending along longitudinal axis416 between and opening at proximal end 406 and distal end 408. Passage402 is sized so that reducing member 400 can be positioned aboutfastener engaging member 380. Reducing member 400 further includes afirst slot 403 to receive first ear 396 therethrough and a diametricallyopposite second slot 405 to receive second ear 398 therethrough. Each ofthe slots 403, 405 opens at the proximal end of reducing member 400.Reducing member 400 is slidable proximally and distally via actuatorassembly 351 along fastener engaging member 380 with longitudinal axes386 and 416 substantially aligned.

As reducing member 400 is moved distally, its distal end 408 contactsrod R and moves it distally towards fastener F. The surgeon can theninsert the set screw or cap through passage 382 of fastener engagingmember 380 to secure rod R in yoke Y. Passage 382 can be sized andconfigured to closely fit with the driver used to install the set screwto ensure proper alignment between the set screw and the yoke. Toprevent reducing member 400 from being extended too far proximally,proximal end 387 of fastener engaging member 380 has a stop member 430,shown also in FIGS. 42-43, secured thereto. Stop member 430 has an innerdiameter that fits over fastener engaging member 380 and is welded orotherwise fastened to its proximal end 387. Stop member 430 has a hollowpassage 432 extending along longitudinal axis 436 that forms anextension of passage 382 of fastener engaging member 380. Stop member430 has an outer diameter 436 that extends about fastener engagingmember 380 and interferes with a driving member 440 secured to proximalend 406 of reducing member 400 to limit proximal movement of reducingmember 400. Stop member 430 further has a length L1 that allows stopmember 430 to extend proximally a sufficient distance from fastenerengaging member 380 to interfere with closed arms 352, 354 of actuatorassembly 350 to limit distal movement of reducing member 400.

As shown in FIGS. 35-37, driving member 440 has a body 446 defining apassage 441 therethrough. Passage 441 has a first larger portion 441 asized to fit over proximal end 406 of reducing member 400 where it iswelded or otherwise attached thereto. Passage 444 is stepped down to asmaller diameter portion 441 b in order to provide a rim 441 c which canbe seated on proximal end 406 of reducing member 400. Smaller portion441 b is sized to slidingly receive fastener engaging member 380therethrough yet allow body 446 to contact stop member 430 to limitproximal movement of reducing member 400 as discussed above.

As shown in FIG. 44, first link 420 includes a body 423 having firsthole 424 at a distal end thereof and a second hole 426 at an oppositeproximal end thereof. Second link 422 is identical to first link 420,and each comprise a portion of actuator assembly 351. Referring back toFIGS. 35-37, driving member 440 further includes a first ear 442 havinga female receptacle 442 a into which one end of first link 420 can beplaced. A pin 363 can be placed through holes 442 b and first hole 424of first link 420 to pivotally couple the distal end of link 420thereto. Similarly, second ear 444 can be provided with a femalereceptacle 444 a into which one end of second link 422 can be placed.Second ear 444 includes holes 444 b in communication with femalereceptacle 444 a. A pin 366 can be placed through holes 444 b topivotally couple the distal end of second link 422 therewith.

Referring now to FIGS. 38-41, first arm 352 and second arm 354 ofactuator assembly 351 will be described. First arm 352 and second arm354 are identical. Each arm 352, 354 extends between a proximal end 356,359 and distal end 358, 361 respectively. Each arm 352, 354 can includean arcuate profile therealong with gripping portions to accommodate thehands and fingers of a surgeon's grip. Distal end 358, 361 includesfemale receptacle 358 a, 361 a having holes 358 b, 361 b incommunication therewith. Female receptacle 358 a, 361 a is sized toreceive respective ones of the ears 396, 398 of fastener engaging member380 therein. Pins 437, 439 extend through respective ones of the holes358 a, 361 a and ears 396, 398 to pivotally couple distal end 358, 361of arms 352, 354 thereto.

Each of the arms 352, 354 has a medially extending female connector 362,365 defining a hole 362 a, 365 a therethrough and a receptacle 362 b,365 b in communication with hole 362 a, 365 a. Receptacles 362 b, 365 bare each sized to receive the proximal end of a respective one of thefirst and second links 420, 422. Pins 367, 369 extend throughthrough-holes 362 a, 365 a to pivotally couple first arm 352 and secondarm 354 to first link 420 and second link 422, respectively. While notrequired, rod reducer instrument 350 can include a locking mechanism(not shown) which holds actuator assembly 351 in its reduced positionshown in FIG. 27.

It is further contemplated that the rod reducer instruments of thepresent invention can be inserted through an access tube used inminimally invasive procedures to install fasteners F and perform otherprocedure on the spine. In FIG. 26, an access tube 450 is shown insection view and positioned through skin S over fastener F and rod R.Such access tubes are used in thorascopic, laparoscopic, and otherminimally invasive approaches to the spine. Since it is contemplatedthat the fastener engaging member and reducing member of the rod reducerinstruments of the present invention can be provided such that they movealong the same central axis, the space needed to reduce rod R isminimized. Thus rod reduction can be accomplished with a minimallyinvasive approach to minimize tissue resection, cutting and the like toaccess the surgical site.

Rod reducer instrument 350 includes a laterally extending member 355,357 extending from each of the arms 352, 354 to contact the proximal endof access tube 450 to limit the insertion depth of rod reducerinstrument 350 therein. It should be understood that such laterallyextending members could be provided with the other rod reducerinstruments described herein, and located on other components thereofsuch as on fastener engaging members 80, 380.

A method for using rod reducer instrument 350 will now be described. Thesurgeon has positioned fastener F into vertebra V1 and placed rod R inclose proximity to yoke Y of fastener F. Rod reducer instrument 350 isin its normally biased open position of FIG. 25 in which arms 352, 354are spaced apart from one another. Rod reducer instrument 350 isintroduced through an open incision or an access port to fastener F.Fastener engaging member 380 is placed around rod R so that rod R is inthe channels formed by slots 391, 393. Distal end 388 can be placed overyoke Y since flex arms 390, 392 move outwardly to pass over yoke Y untilprotrusions 394, 396 engage indentations in yoke Y. Arms 352, 354 aremoved towards one another to move reducing member 400 distally alongfastener engaging member 380 to push or reduce rod R into yoke Y asufficient distance to allow attachment of a set screw or cap to yoke Y.This distal movement of reducing member 400 is effected by the first andsecond links 420, 422 pivoting at their ends coupled to arms 352, 354and also pivoting at their ends coupled to driving member 440, whichthereby drives reducing member 400 distally and into contact with rod R.Actuator assembly 351 can be held in the position of FIG. 27 to maintainrod R in its reduced position as the surgeon installs the set screw inyoke Y through passage 382 of fastener engaging member 380. Once the setscrew is firmly seated against rod R, arms 352, 354 are released andreturned to their open position of FIG. 25. Flex arms 390 and 392 allowrelease of protrusions 394, 396 from yoke Y. Rod reducer instrument 350can then be removed and repeated as needed to reduce rod R into otherfasteners.

The rod reducer instruments of the present invention are preferably madeof a sturdy biocompatible material such as stainless steel usingstandard fabrication techniques for medical grade instruments. However,other biocompatible materials are also contemplated.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected.

What is claimed is:
 1. A surgical instrument for reducing a rod toward abone fastener, comprising: a fastener engaging member extending betweena proximal end and a distal end, a distal portion of said fastenerengaging member being adapted to receive a portion of the rod thereinand being further adapted to engage the bone fastener; a reducing membermovably disposed about said fastener engaging member, said reducingmember having a distal end; and an actuator assembly pivotally coupledto said fastener engaging member and pivotally coupled to said reducingmember, wherein said actuator assembly is operable to move said reducingmember distally with respect to said fastener engaging member wherebysaid distal end of said reducing member contacts the rod to move the rodtoward the bone fastener.
 2. The instrument of claim 1, wherein saidactuator assembly includes a lateral offset to position a proximalportion of said actuator assembly away from a proximal end opening of apassage extending through said fastener engaging member.
 3. Theinstrument of claim 1, wherein said actuator assembly includes a firstarm pivotally coupled to a second arm.
 4. The instrument of claim 3,wherein: said first arm includes a joint between a proximal end and adistal end of said first arm, said joint defining a proximal portion anda distal portion of said first arm; said second arm includes a jointbetween a proximal end and a distal end of said second arm, said jointdefining a proximal portion and a distal portion of said second arm; andsaid proximal portion of said first arm and said proximal portion ofsaid second arm are each pivotal about a respective one of said jointsto orient said proximal portions transversely to said distal portions.5. The instrument of claim 1, wherein said actuator assembly includes alocking mechanism to hold said reducing member in a reduced position. 6.The instrument of claim 1, wherein said actuator assembly is springbiased to a reducing member retracted position.
 7. The instrument ofclaim 1, wherein said fastener engaging member includes a pair of flexarms extending proximally from said distal end thereof.
 8. Theinstrument of claim 7, wherein said fastener engaging member includes aprong at the distal end of each of said flex arms, each of said prongsdefining a channel for receiving the rod therein.
 9. The instrument ofclaim 8, wherein said reducing member is positionable over at least aportion of said prongs.
 10. The instrument of claim 7, wherein saidfastener engaging member includes a pair of elongated slots extendingbetween said flex arms opening at said distal end.
 11. The instrument ofclaim 10, wherein said reducing member includes at least one slotthrough a sidewall thereof in communication with one of said elongatedslots of said fastener engaging member.
 12. The instrument of claim 1,wherein said fastener engaging member and said reducing member arereciprocally slidably coupled.
 13. The instrument of claim 1, whereinsaid reducing member and said fastener engaging member each include agenerally circular cross-section.
 14. The instrument of claim 1,wherein: said fastener engaging member has a longitudinal axis extendingproximally and distally therethrough; and said reducing member has alongitudinal axis extending proximally and distally therethrough, saidlongitudinal axis of said reducing member being generally positionedalong said longitudinal axis of said fastener engaging member.
 15. Theinstrument of claim 1, wherein said actuator assembly includes: a firstlink having a distal end pivotally coupled to a first side of saidreducing member; a first pivot arm having a distal end pivotally coupledto a proximal end of said first link, said first pivot arm having amedially extending connector pivotally coupled to said fastener engagingmember; a first arm having a distal end pivotally coupled to a proximalend of said first pivot arm, said first arm having a proximal portionextending proximally from a medially extending connector; a second linkhaving a distal end pivotally coupled to a second side of said reducingmember opposite said first side; a second pivot arm having a distal endpivotally coupled to a proximal end of said second link, said secondpivot arm having a medially extending connector pivotally coupled tosaid medially extending connector of said first pivot arm and alsopivotally coupled to said fastener engaging member; and a second armhaving a medially extending connector pivotally coupled to said mediallyextending connector of said first arm, said second arm having a distalend pivotally coupled to a proximal end of said second pivot arm, saidsecond arm further having a proximal portion extending proximally ofsaid medially extending connector of said second arm.
 16. The instrumentof claim 1, wherein said actuator assembly includes: a first link havinga distal end pivotally coupled to said reducing member; a first armhaving a distal end pivotally coupled to said fastener engaging member,said first arm extending to a proximal end, said first arm further beingpivotally coupled between said proximal and distal ends to a proximalend of said first link; a second link having a distal end pivotallycoupled to said reducing member opposite said first link; and a secondarm having a distal end pivotally coupled to said fastener engagingmember opposite said first arm, said second arm extending to a proximalend and being pivotally coupled between said proximal and distal ends toa proximal end of said second link.
 17. The instrument of claim 16,further comprising a stop member at said proximal end of said fastenerengaging member to limit proximal movement of said reducing member. 18.A surgical instrument for reducing a rod toward a bone fastener,comprising: a fastener engaging member having a passage extendingbetween a proximal end and a distal end, a distal portion of saidfastener engaging member being adapted to receive a portion of the rodtherein and being further adapted to engage the bone fastener; areducing member movably disposed with respect to said fastener engagingmember, said reducing member having a distal end; an actuator assemblycoupled between said fastener engaging member and said reducing memberand including a proximal portion extending proximally of said reducingmember and said fastener engaging member, wherein: said actuatorassembly includes a lateral offset portion to locate said proximalportion of said actuator assembly away from a proximal end opening ofsaid passage of said fastener engaging member; and said actuatorassembly is operable to move said reducing member distally with respectto said fastener engaging member whereby said distal end of saidreducing member contacts the rod to move the rod toward the bonefastener.
 19. The instrument of claim 18, wherein said reducing memberis positioned about said fastener engaging member and slidable withrespect thereto in response to operation of said actuator assembly. 20.The instrument of claim 19, wherein said distal end of said fastenerengaging member includes a pair of prongs forming a rod passage.
 21. Theinstrument of claim 20, wherein said reducing member and said distal endof said fastener engaging member are configured such that said reducingmember exerts inward pressure on at least one of said prongs when saidreducing member is positioned over said prongs.
 22. The instrument ofclaim 18, wherein: said fastener engaging member has a longitudinal axisextending proximally and distally therethrough; and said reducing memberhas a longitudinal axis extending proximally and distally therethrough,said longitudinal axis of said reducing member being generallypositioned along said longitudinal axis of said fastener engagingmember.
 23. The instrument of claim 18, wherein said actuator assemblyincludes: a first link having a distal end pivotally coupled to a firstside of said reducing member; a first pivot arm having a distal endpivotally coupled to a proximal end of said first link, said first pivotarm having a medially extending connector pivotally coupled to saidfastener engaging member; a first arm having a distal end pivotallycoupled to a proximal end of said first pivot arm, said first arm havinga medially extending connector; a second link having a distal endpivotally coupled to a second side of said reducing member opposite saidfirst side; a second pivot arm having a distal end pivotally coupled toa proximal end of said second link, said second pivot arm having amedially extending connector pivotally coupled to said mediallyextending connector of said first pivot arm and also pivotally coupledto said fastener engaging member; and a second arm having a mediallyextending connector pivotally coupled to said medially extendingconnector of said first arm, said second arm having a distal endpivotally coupled to a proximal end of said second pivot arm.
 24. Theinstrument of claim 18, wherein said actuator assembly includes: a firstlink having a distal end pivotally coupled to said reducing member; afirst arm having a distal end pivotally coupled to said fastenerengaging member, said first arm extending to a proximal end, said firstarm further being pivotally coupled between said proximal and distalends to a proximal end of said first link; a second link having a distalend pivotally coupled to said reducing member opposite said first link;and a second arm having a distal end pivotally coupled to said fastenerengaging member opposite said first arm, said second arm extending to aproximal end and being pivotally coupled between said proximal anddistal ends to a proximal end of said second link.
 25. The instrument ofclaim 18, wherein said actuator assembly includes a first arm pivotallycoupled to a second arm.
 26. The instrument of claim 25, wherein: saidfirst arm includes a joint between a proximal end and a distal end ofsaid first arm, said joint defining a proximal portion and a distalportion of said first arm; said second arm includes a joint between aproximal end and a distal end of said second arm, said joint defining aproximal portion and a distal portion of said second arm; and saidproximal portion of said first arm and said proximal portion of saidsecond arm are each pivotal about a respective one of said joints toorient said proximal portions transversely to said distal portions. 27.The instrument of claim 25, wherein said first arm and said second armare spring biased away from one another.
 28. The instrument of claim 18,wherein said actuator assembly includes a locking mechanism to hold saidreducing member in a reduced position.
 29. The instrument of claim 18,wherein said fastener engaging member includes a pair of flex armsextending proximally from said distal end thereof.
 30. The instrument ofclaim 29, wherein each of said flex arms includes a prong at a distalend thereof, each of said prongs defining a channel for receiving therod therein.
 31. The instrument of claim 30, wherein said fastenerengaging member includes a pair of elongated slots extending betweensaid flex arms to said distal end.
 32. A surgical instrument forreducing a rod toward a bone fastener, comprising: a fastener engagingmember extending between a proximal end and a distal end, a distalportion of said fastener engaging member being adapted to engage thebone fastener; a reducing member disposed about said fastener engagingmember; an actuator assembly coupled between said fastener engagingmember and said reducing member and operable to move said reducingmember about said fastener engaging member between a reduced positionand a retracted position, wherein said actuator assembly includes: afirst link having a distal end pivotally coupled to a first side of saidreducing member; a first pivot arm having a distal end pivotally coupledto a proximal end of said first link, said first pivot arm having amedially extending connector pivotally coupled to said fastener engagingmember; a first arm having a distal end pivotally coupled to a proximalend of said first pivot arm, said first arm having a medially extendingconnector; a second link having a distal end pivotally coupled to asecond side of said reducing member opposite said first side; a secondpivot arm having a distal end pivotally coupled to a proximal end ofsaid second link, said second pivot arm having a medially extendingconnector pivotally coupled to said medially extending connector of saidfirst pivot arm and also pivotally coupled to said fastener engagingmember; and a second arm having a medially extending connector pivotallycoupled to said medially extending connector of said first arm, saidsecond arm having a distal end pivotally coupled to a proximal end ofsaid second pivot arm.
 33. The instrument of claim 32, wherein: saidfirst arm includes a joint between a proximal end and a distal end ofsaid first arm, said joint defining a proximal portion and a distalportion of said first arm; said second arm includes a joint between aproximal end and a distal end of said second arm, said joint defining aproximal portion and a distal portion of said second arm; and saidproximal portion of said first arm and said proximal portion of saidsecond arm are each pivotal about a respective one of said joints toorient said proximal portions transversely to said distal portions. 34.The instrument of claim 32, wherein said first arm and said second armare spring biased away from one another.
 35. The instrument of claim 32,wherein said actuator assembly includes a locking mechanism at theproximal ends of said first and second arms to hold said reducing memberin a reduced position.
 36. The instrument of claim 32, wherein saidfirst pivot arm and said second pivot arm each include a lateral offsetto locate a proximal portion of the actuator assembly away from aproximal end opening of said fastener engaging member.
 37. A surgicalinstrument for reducing a rod toward a bone fastener, comprising: afastener engaging member extending between a proximal end and a distalend, a distal portion of said fastener engaging member being adapted toengage the bone fastener; a reducing member disposed about said fastenerengaging member; an actuator assembly coupled between said fastenerengaging member and said reducing member and operable to move saidreducing member about said fastener engaging member between a reducedposition and a retracted position, wherein said actuator assemblyincludes: a first link having a distal end pivotally coupled to saidreducing member; a first arm having a distal end pivotally coupled tosaid fastener engaging member, said first arm extending to a proximalend, said first arm further being pivotally coupled between saidproximal and distal ends to a proximal end of said first link; a secondlink having a distal end pivotally coupled to said reducing memberopposite said first link; and a second arm having a distal end pivotallycoupled to said fastener engaging member opposite said first arm, saidsecond arm extending to a proximal end, said second arm further beingpivotally coupled between said proximal and distal ends to a proximalend of said second link.
 38. The instrument of claim 37, wherein saidactuator assembly, said reducing member, and said fastener engagingmember have a common central axis.
 39. The instrument of claim 37,wherein said first arm and said second arm each include a laterallyextending blocking arm for contacting a proximal end of an access tubeand limiting the insertion depth of the surgical instrument therein. 40.A surgical instrument for reducing a rod toward a bone fastener,comprising: a fastener engaging member extending between a proximal endand a distal end, a distal portion of said fastener engaging memberbeing adapted to receive a portion of the rod therein and being furtheradapted to engage the bone fastener; a reducing member having a bodymovably disposed about said fastener engaging member, said body havingan extension portion extending proximally from a distal end of saidreducing member; and an actuator assembly operable to move said reducingmember distally with respect to said fastener engaging member wherebysaid distal end of said reducing member contacts the rod to move the rodtoward the bone fastener, wherein said reducing member can be moveddistally so that said extension portion is positioned distally of saiddistal end of said fastener engaging member.
 41. The instrument of claim40, wherein said reducing member defines a passage extending between aproximal end and a distal end thereof.
 42. The instrument of claim 41,wherein said passage has a distal portion defined by said extensionportion and proximal portion extending from said distal portion to saidproximal end of said reducing member, said reducing member defining alip between said proximal and distal portions of said passage.
 43. Theinstrument of claim 42, wherein said fastener engaging member has anenlarged rim about its distal end, said rim contacting said lip toestablish a predetermined reduction distance for said extension portionwith respect to said fastener engaging member.
 44. A method of reducingan elongated implant member in orthopedic surgery, comprising: fixing afastener to a patient; placing an elongated implant member adjacent saidfastener; providing a rod reducer instrument; inserting said rod reducerinstrument through an access tube providing access to said fastener andsaid elongated implant member; placing a distal portion of a fastenerengaging member of said rod reducer instrument over said elongatedimplant member; engaging said distal portion of said fastener engagingmember to said fastener; and moving a reducing member distally about thefastener engaging member so that said reducing member contacts saidelongated implant member and forces said elongated implant member towardsaid fastener.
 45. The method of claim 44, further comprising: movingsaid reducing member to position said elongated implant member at afirst location in the yoke of the fastener; and engaging said elongatedimplant member in said yoke with a set screw inserted through a passagedefined by said fastener engaging member.
 46. A method of reducing anelongated implant member in orthopedic surgery, comprising: fixing firstand second fasteners to a patient; placing an elongated implant memberadjacent said first and second fasteners; providing a rod reducerinstrument; placing a distal portion of a fastener engaging member ofsaid rod reducer instrument over said elongated implant member; engagingsaid distal portion of said fastener engaging member of said rod reducerinstrument to said fastener; moving a reducing member of said rodreducer instrument distally with respect to said fastener engagingmember so that said rod reducer instrument contacts said elongatedimplant member and forces said elongated implant member a first distancetoward said first fastener; securing said elongated implant member tosaid first fastener; modifying said rod reducer instrument; placing thedistal portion of the fastener engaging member of the modified rodreducer instrument over said elongated implant member; engaging saiddistal portion of said fastener engaging member of said modified rodreducer instrument to said second fastener; moving said reducing memberof said modified rod reducer instrument distally with respect to saidfastener engaging member so that said modified rod reducer instrumentcontacts said elongated implant member and forces said elongated implantmember a second distance toward said second fastener, said seconddistance being different than said first distance; and securing saidelongated implant member to the second fastener.
 47. The method of claim46, wherein securing said elongated implant member includes engagingsaid elongated implant member in a yoke of said first and secondfasteners with a set screw inserted through a passage defined by saidfastener engaging member of each of said rod reducer instrument and saidmodified rod reducer instrument.